European physical journal-applied physics vol:14 issue:3 pages:165-169
An interesting method based on a variable splitting into two time-scales, the "transient time harmonic method" is proposed allowing to compute transient phasor solutions of problems involving slow, close to quasi-static and fast dynamics simultaneously, yielding stiff properties. The time-step of the dynamic problem can be chosen larger than the fundamental time interval, resulting in an "envelope" model for the problem with the small time constant. The derivation of the FEM matrices is discussed. Examples, including a transformer operating a slow varying load and a transient coupled electromagnetic-thermal problem, are discussed.